Heat exchangers of the plate type are comprised of pairs of preformed plates joined to other pairs at their ends by integral bosses and separated at their middle section by air centers or corrugated fins, the plates and fins all being brazed together so that each pair of plates becomes a tube for carrying refrigerant, the bosses serving as a manifold for permitting refrigerant flow from one tube to another, and the fins facilitating heat exchange between the tubes and air flowing outside the tubes. U.S. Pat. No. 4,470,455 issued to Sacca describes such a plate type heat exchanger in detail.
The assembly of the plate type heat exchanger elements into a core ready for brazing has typically been carried out largely by hand operations. Specifically, the first step is to assemble a fin element between two plates and crimp the plates together into subassemblies where their bosses connect, and then manually stack such subassemblies along with side plates into a fixture which holds each subassembly in place.
It is desirable to enhance the assembly practice by an improved method and machine for assembly. In particular it has been found that the process is improved in terms of automation and in terms of reducing spacing in the fixture if it is begun by joining the plates together into pairs that eventually become tubes and inserting the plate pairs and side plates into a fixture and then inserting the centers between the plates. It is desirable to have a machine to perform the assembly operations to reduce the manufacturing expense and otherwise improve the efficiency of the assembly practice. It has been demonstrated that the machine assembly of plate pairs, air centers and side plates into a pallet is practical.
To economically assemble the elements it is desirable to avoid large inventories of parts and any nonessential handling of the parts. Here it is proposed to manufacture at least some of the parts adjacent the loading station and directly feed the parts to the pallet. Thus plate pairs are assembled and immediately dropped into the pallet so that there is no inventory of plate pairs. Also machines for manufacturing the air centers discharge each center directly into the pallet at the loading station so that the centers are inserted into assemblies as fast as they can be produced. This requires the synchronization of the manufacturing apparatus and the assembly apparatus. In particular, the center manufacture is essentially a rolling mill operation which is a continuous process so that parts are made at an optimum rate. While variation of the rate is possible, there are limitations on how fast the rate can be changed so that it is not practical to stop the machine suddenly and restart the machine to accommodate discontinuous assembly procedures. Rather, it is preferred to accommodate the assembly method and apparatus to the center manufacture.